Fixing fatal error caused by associated models using a datasource tha…

…t is not a subclass of dbo_source. Test added. Fixes #873

cake/libs/model/datasources/dbo_source.php

@@ -841,7 +841,7 @@ function read(&$model, $queryData = array(), $recursive = null) {
 						$db =& $this;
 					}
 
-					if (isset($db)) {
+					if (isset($db) && method_exists($db, 'queryAssociation')) {
 						$stack = array($assoc);
 						$db->queryAssociation($model, $linkModel, $type, $assoc, $assocData, $array, true, $resultSet, $model->recursive - 1, $stack);
 						unset($db);

cake/tests/cases/libs/model/datasources/dbo_source.test.php

@@ -1339,6 +1339,7 @@ function getLastQuery() {
 	function endTest() {
 		unset($this->Model);
 		Configure::write('debug', $this->debug);
+		ClassRegistry::flush();
 		unset($this->debug);
 	}
 
@@ -4441,4 +4442,19 @@ function testFullTablePermutations() {
 		$result = $this->testDb->fullTableName($Article, false);
 		$this->assertEqual($result, 'tbl_articles');
 	}
+
+/**
+ * test that read() only calls queryAssociation on db objects when the method is defined.
+ *
+ * @return void
+ */
+	function testReadOnlyCallingQueryAssociationWhenDefined() {
+		ConnectionManager::create('test_no_queryAssociation', array(
+			'datasource' => 'data'
+		));
+		$Article =& ClassRegistry::init('Article');
+		$Article->Comment->useDbConfig = 'test_no_queryAssociation';
+		$result = $Article->find('all');
+		$this->assertTrue(is_array($result));
+	}
 }